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  1. #1
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    FOX DHX 4.0/5.0 SSD custom mod and tuning: AVALANCHE

    Craig at avalanche downhill racing is now doing FOX DHX shocks, the modifications and tuning swap stuff out and custom parts put in making it Speed Sensative damping.

    Talked to him the other day after seeing it on the site I have my dhx 5.0 from my Sunday being done.

    Link
    Fox DHX 5.0Speed sensitive Damper Adjuster Kit

    Fox DHX 5.0/4.0 and VanRC Speed Sensitive DamperAdjuster Kit

    Replaces ProPedal Adjuster with a low speed compression adjuster and custom valved high speed piston system in the existing Fox piggyback housing. This conversion complements the revalved main piston to completely convert the DHX/VanRC to a true speed sensitive damper.

    Technical Discussion Here:

    Includes revalve and setup for rider, frame and conditions.

    Also includes complete rebuild service, new improved seals, oil, nitrogen charge and typical wear parts* included in price

    *(Typical wear parts: shaft seal, dust scraper, shaft bushing, reducer DU bushings, and o-rings)

    Optional:

    Shape factor bottom-out bumper (Available now)

    Reservoir Volume Expansion Kit, standard length or extended length (Available Soon).

    Not available as a self install kit.

    Available soon, DHX 3.0 optimized SSD internal replacement Valve, research being done currently on viability of DHX Air shock conversions to SSD technology





    Why change out Propedal valve in the DHX?....The design of the Propedal creates a great position sensitive shock. As the pressure in the shock goes up the propedal valve gets harder to open, this creates more compression damping. The pressure can be increased 3 ways, first my adding more air pressure to the schrader valve, second as the shaft compresses, the displaced oil compresses the reservoir floating piston down, which drives up the pressure in the reservoir, and lastly the chamber compensation bottom out can be dialed in to decrease the reservoir volume and thus cause the pressure to be driven up even faster as the shaft compresses. The Propedal adjuster allows the rider to compensate for the pressure on the valve by applying opposite spring pressure to the valve reducing the force required to overcome this internal pressure and allowing the valve to blow-off more easily.

    So this all sounds great but in a real world where courses and terrain are not perfectly smooth and void of square edge holes, this is where the Propedal system fails to allow the valve to blow-off. When the shock hits square edge bumps deep in the stroke the valve becomes harder to blow-off and is actually getting firmer the deeper it gets in the travel (Position sensitive damper).

    This is why the Speed Sensitive Damper (SSD) is preferred, as the shaft speed needs to increase the compression adjustment valve needs to blow-off when the bumps become square edged or what we call high speed hits. This creates the need for the conversion and replacement of the propedal system to a shimmed ported valve. Since the shim stiffness is not affected by the build up of pressure in the reservoir, the shims can create damping at low and medium speed compression hits and be valved to blow-off when higher shaft speeds occur thus allowing the damper to smoothly resist the square edged hits. Because the main piston was valved for a very progressive position sensitive Propedal valve we can now revalve the main piston to contribute to the compression circuit and due to the decreased ramp up in the overall spring rate of the damper, the rebound stack can be revalved to be more linear . The main piston can now control it's 70% share of the compression damping giving us many more tuning options for rider set-ups. Rebound can be tuned to be more reactive on small bumps and provide lift where needed while preventing that pogo stick feel.

    Specifications:

    16 mm Speed Sensitive flow controlled 4 port Compression Valve 15 Clicks of Low Speed Compression, uses exiting Propedal knob as new low speed adjuster Revalvable 6 mm ID shims High speed adjustment - Internal Shim Stack Nitrogen charged to 160 psi, fixed (i.e. no need for adjustment now) Retains bottom out system to aid with pressure ramp up needed for regressive linkage frames Installs directly into the DHX housing...which preserves same top housing and adjuster knob for fit compatability of existing frame applications Low friction main shaft Seal Shape Factor Bottom-out Bumper, optional Increased volume Reservoir cap, optional Extended Reservoir cap for maximum volume, optional
    Last edited by bullcrew; 12-17-2011 at 09:09 PM.
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  2. #2
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    Noice!
    Ruder than you.
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  3. #3
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    This was on the website forever for preorder, glad to hear its reality now. Do you know if it's the same as Push's mx tune and how it compares?

  4. #4
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    Quote Originally Posted by ifouiripilay View Post
    This was on the website forever for preorder, glad to hear its reality now. Do you know if it's the same as Push's mx tune and how it compares?
    This has a bunch of stuff removed and a bunch of custom parts craig designed and stuck in. It will be a full race tune or freeride whichever is the riders style it can have more or les valving it can be shimmed and if you have a regressive bike ie like my Sunday the bottom out adjuster can be cranked in to accommodate some progressiveness to help it.
    This actually adds a low speed compression with needle valve on the end of the pro pedal.

    This is actually a really tuneable shock with the bottom out left on to make the shock go from linear to progressive it will and can accommodate a bunch of applications.


    By leaving the bottom out on its like having 2 shocks in one, crank it up and make the bike poppy and swap lines and jumps at will.
    Hit a chatter rocky course back the bottom out back and have a total linear speed sensative shock.


    Like stated above it is like having 2 shocks in 1
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  5. #5
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    How would this compare to the PUSH mod which also removes the platform damping and they've been doing this to that shock for over 7 years now?

    Have FUN!

    G MAN
    "There's two shuttles, one to the top and one to the hospital" I LOVE this place!!!

  6. #6
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    Quote Originally Posted by Gman086 View Post
    How would this compare to the PUSH mod which also removes the platform damping and they've been doing this to that shock for over 7 years now?

    Have FUN!

    G MAN
    Similar except I don't think they set the propedal up as a low speed compression setting complete with new needle valve assembly and internals for it.


    And its cheaper with that as well.
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  7. #7
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    Do you know if it's the same as Push's mx tune and how it compares?
    Our system offers both High and Low Speed adjustment externally. The avalanche uses preset high speed valving with external Low Speed control. Craig makes really nice stuff so I have no doubt this will be a nice unit.

    By leaving the bottom out on its like having 2 shocks in one, crank it up and make the bike poppy and swap lines and jumps at will.
    Hit a chatter rocky course back the bottom out back and have a total linear speed sensative shock.
    By removing the Boost Valve and replacing it with a SSD valve you no longer have the bottom out feature. Turing the bottom out control will cause a slight increase in lifting force at the piston but at the expense of causing the shock to heat more rapidly than running it all of the way out. So basically, you'd decrease small bump sensitivity slightly, not really have any effect on bottoming control, and increase heat.

    Similar except I don't think they set the propedal up as a low speed compression setting complete with new needle valve assembly and internals for it.
    We machine our own knobs, but yes our low speed circuit utilizes a needle and valve seat.

    Darren

  8. #8
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    Quote Originally Posted by PUSHIND View Post
    Our system offers both High and Low Speed adjustment externally. The avalanche uses preset high speed valving with external Low Speed control. Craig makes really nice stuff so I have no doubt this will be a nice unit.

    By removing the Boost Valve and replacing it with a SSD valve you no longer have the bottom out feature. Turing the bottom out control will cause a slight increase in lifting force at the piston but at the expense of causing the shock to heat more rapidly than running it all of the way out. So basically, you'd decrease small bump sensitivity slightly, not really have any effect on bottoming control, and increase heat.

    We machine our own knobs, but yes our low speed circuit utilizes a needle and valve seat.

    Darren
    Good point it would be a increase in rate causing more internal pressure and heat vs making the shock ramp up.

    Good to know that you did a needle valve wasn't sure and didn't see it listed on your site under the what's done.
    I assume that's with the whole mx tune new bridge that the low speedneedle and seat is included.
    good to see you chime in.
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  9. #9
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    Quote Originally Posted by PUSHIND View Post
    Our system offers both High and Low Speed adjustment externally. The avalanche uses preset high speed valving with external Low Speed control. Craig makes really nice stuff so I have no doubt this will be a nice unit.

    Darren
    When will your system be in stock? Why is it difficult to keep in stock?

    Good to see another option with Avy. Craig does awesome work.

  10. #10
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    Good to know that you did a needle valve wasn't sure and didn't see it listed on your site under the what's done.
    I assume that's with the whole mx tune new bridge that the low speedneedle and seat is included.
    With our Factory Tuning System, we modify the existing system to. With the MX-Tune we use the needle.

    When will your system be in stock? Why is it difficult to keep in stock?
    MX-Tune will be available in a few weeks. We just underestimated the demand by a long shot and were having and outside vendor make a few of the pieces. Instead of reordering a couple of the CNC lathe parts, we decided to purchase this:



    Haas was a little late building it, but it's been in house and online making production parts for a couple of weeks now.

    Darren

  11. #11
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    So aside of the external high speed compression the avalanche tune is the same as your mx tune just cheaper? Plus you get low speed adjustability a custom tuned shim stack and options for larger reservoir capacity, propedal removed completely and cheaper than the your race tune.



    I know high speed internal set ups are controlled by shims and can be made to blow off or fold at different pressure via speed. Are you putting different springs on your high speed to blow off at different pressures for different designs?
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  12. #12
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    So aside of the external high speed compression the avalanche tune is the same as your mx tune just cheaper? Plus you get low speed adjustability a custom tuned shim stack and options for larger reservoir capacity, propedal removed completely and cheaper than the your race tune.
    Well, first we feel like the external High Speed compression adjust is a pretty big deal. Second, we also install not only new custom shim stacks, but a new CNC machined PUSH piston (See Below) to go along with the stacks. We also install our proprietary piston bolt with built in asymmetric valve which makes the compression and rebound circuits completely independent from each other (this was a PUSH exclusive up until Trek started offering it this past year in the Session RC4 shocks that FOX is building). Proprietary seals and wipers specifically designed to work with the aluminum shafts, high volume end caps for increased reservoir capacity, the ability to eliminate the Propedal effect, proprietary rod bumpers, etc. So, yes the AVA kit is cheaper, but it's because of the additional machined parts that we install. If we were to just do a revalve without our piston, or piston bolt, etc then we could probably hit that price point as well.

    I know high speed internal set ups are controlled by shims and can be made to blow off or fold at different pressure via speed. Are you putting different springs on your high speed to blow off at different pressures for different designs?
    Yes, we have 4 different High Speed blow-off springs available depending on the application and leverage characteristic.

    Listen, obviously I'm biased towards our products and services. Craig is a really talented guy, and although I haven't seen this product yet I'm sure it is going to work really well and will be a great fit for a lot of riders. We just have a different approach that works for us and our customers.

    Darren
    Attached Thumbnails Attached Thumbnails FOX DHX 4.0/5.0  SSD custom mod and tuning: AVALANCHE-monarch-piston.jpg  


  13. #13
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    Any chance PUSH or Avy will offer tunes for the DHX RC2?

  14. #14
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    Any chance PUSH or Avy will offer tunes for the DHX RC2?
    We definitely are. We had a custom wiper molded for us which we're currently waiting on before releasing our production kit.

    Darren

  15. #15
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    At least Craig answers my emails
    I admit....not my strong suit! That's why we have Nick! nickb@pushindustries.com. He's our email guy, and unlike me, really easy to get a hold of.

    Shoot, if it wasn't for this CNC programming problem I've been dealing with all day, I wouldn't have been at my desk all this time available to post on emptybeer!

    Darren

  16. #16
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    At least Craig answers my emails

  17. #17
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    So went and looked for the dhx tech page and there's really'intresting data on How the fox ramps up as well as internal pressure of the modded and extended resevoirs and new Internal seals dust wiper and bottom out bumper.

    The pressure internally that a stock dhs reaches in the platform (reservoir) at bottom out A dhx 5.0 with 3" stroke Stock PS I 1500+ No bottom out 625 Modified 380 Extended resevoir 225

    The stock is for regressive, no bottom out and modified is for regresive to linear Modified is for linear to progressive And extended reservoir is for progressive to rising rate


    Fox DHX 5.0Speed sensitive Damper Adjuster Kit
    Last edited by bullcrew; 01-04-2012 at 09:46 PM.
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  18. #18
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    Let me first say the stock reservoir was left to make this shock ramp for a progressive setup (ie Sunday).


    Got a late Xmas present in today.

    Had a little time today on it but will update after beating on it.
    The rebound has a very big range that is noticeable between clicks, the comoression (low speed) has a very nice wide range to dial in. It ramps but doesn't pack up or spike. I'll try and grab some pics from the rocks and jumps on wed. I will have a diversified run on it, it feels better than the rock wc did. It has the same deep feel but now I can pop it up and around so definently not dead feeling.







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  19. #19
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    Quote Originally Posted by bullcrew View Post
    Let me first say the stock reservoir was left to make this shock ramp for a progressive setup (ie Sunday).


    Got a late Xmas present in today.

    but doesn't pack up or spike. I'll try and grab some pics from the rocks and jumps on wed. I wilg]
    man you should have rode.....end of month???
    the trick is ENJOYING YOUR LIFE EACH DAY, don't waste them away wishing for better days

  20. #20
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    Quote Originally Posted by SHIVER ME TIMBERS View Post
    man you should have rode.....end of month???
    I wanted to but too much stuff going on that I make local stuff which by all account t is golden but my time has been super limited.
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  21. #21
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    Quote Originally Posted by bullcrew View Post
    I wanted to but too much stuff going on that I make local stuff which by all account t is golden but my time has been super limited.

    maybe I will come down....
    the trick is ENJOYING YOUR LIFE EACH DAY, don't waste them away wishing for better days

  22. #22
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    Quote Originally Posted by SHIVER ME TIMBERS View Post
    maybe I will come down....
    Yeah if you come down B you can stay here at the house.
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  23. #23
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    Quote Originally Posted by bullcrew View Post
    Yeah if you come down B you can stay here at the house.
    the trick is ENJOYING YOUR LIFE EACH DAY, don't waste them away wishing for better days

  24. #24
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    fox dhx air 5.0

    so i have this fox dhx air 5.0 and it has leaked oil since day one. it's on a ventana la bruja bike and needs some lovin. i don't want to send it back to fox and have the seals leak again so who should i have rebuild it (push) or ? ...ralph
    i need to ride more. building jumps takes to much time...my other hobby is kicking the crap outta my home built mook jong.

  25. #25
    ventanakaz
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    so i have this fox dhx air 5.0 and it has leaked oil since day one. it's on a ventana la bruja bike and needs some lovin. i don't want to send it back to fox and have the seals leak again so who should i have rebuild it (push) or ? ...ralph
    i need to ride more. building jumps takes to much time...my other hobby is kicking the crap outta my home built mook jong.

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